Step 1: Find valence e- for all atoms. Add them together.

H:1x2=2
O:6

Total=8

Step2: Find octet e- for each atom and add them together.

H:2x2=4
O:8

Total=12

Step3: Gives you bonding e-. Subtract step 1 total from step 2

12-8=4e-

Step 4: Find number of bonds by diving the number in step 3 by 2(because each bond is made of 2 e-)

4e-/2= 2 bond pairs

Step 5: Find the number of nonbonding (lone pairs) e-. Subtract step 3 number from step 1.

8-4= 4e-=2 lone pair

Use information from step 4 and 5 to draw the lewis structure.

Oxygen  goes in the centre.

Lewis dot structure of H₂O

Alternatively a dot method can be used to draw the lewis structure.
Calculate the total valence electrons in the molecule.
H:1x2=2
O:6

Total=8

Put oxygen in center and arrange hydrogen atoms on the sides.put a pair of electrons connecting hydrogen with oxygen and the remaining four electrons on oxygen..